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A048049 Denominator of Sum_{k=1..n} 1/phi(k). 6

%I

%S 1,1,2,1,4,4,12,6,3,12,60,15,60,60,120,30,240,80,720,720,720,720,7920,

%T 7920,1584,1584,1584,1584,11088,11088,55440,13860,1386,11088,11088,

%U 11088,11088,11088,11088,5544,6930,13860,13860,3465,27720,27720,637560,1275120,182160

%N Denominator of Sum_{k=1..n} 1/phi(k).

%D D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, Section I.27.

%H Robert Israel, <a href="/A048049/b048049.txt">Table of n, a(n) for n = 1..10000</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/TotientSummatoryFunction.html">Totient Summatory Function</a>

%e 1, 2, 5/2, 3, 13/4, 15/4, 47/12, 25/6, 13/3, 55/12, 281/60, 74/15, ...

%p map(denom, ListTools:-PartialSums(map(1/numtheory:-phi, [$1..100]))); # _Robert Israel_, Apr 16 2019

%Y Cf. A000010, A028415.

%K nonn,frac

%O 1,3

%A _N. J. A. Sloane_, Jun 28 2002

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Last modified August 13 22:31 EDT 2020. Contains 336464 sequences. (Running on oeis4.)